A solution of 4-pyridyl-t-butydimethylsilyloxymethyl 4-t-butylphenyl ketone from Step C (170 mg, 0.44 mmol), copper (II) acetate (161 mg, 0.89 mmol), ammonium acetate (342 mg, 4.44 mmol) and 4-chlorobenzaldehyde (78 mg, 0.56 mmol) in acetic acid (3 mL) was heated to 110° C. for 5 h. The reaction mixture was then cooled to 0° C. and ice (4 g), ethyl acetate (4 mL) and concentrated ammonium hydroxide solution (4 mL) were added. After stirring for 30 min, the phases were separated and the aqueous layer extracted with ethyl acetate (2 times). The combined organic phases were successively washed with water (2 times) and saturated salt solution and dried over anhydrous sodium sulfate. The mixture was filtered and the solvent removed by rotoevaporation. The residue was purified by flash column chromatography on silica gel eluted with 0-3% methanol in methylene chloride to yield the title compound as a pale yellow solid 102 mg, 59% yield), mass spectrum (CI) m/e=388 (M+1)+.
